LOWER CHALK—DEVONSHIRE. 
139 
From all the facts I think we may conclude that the two clearly- 
marked planes of division which are seen above Beds A and B re¬ 
spectively below the Coastguard Station are really planes of erosion ; 
that both these beds, A and B, were originally deposited over the 
tract where one or both are now absent, but that this tract was 
swept by a strong current which at the two epochs indicated by 
the erosion-planes became strong enough to carry away and destroy 
some of the material it had previously deposited. 
The very thickening of the beds from Beer Head westward suggests 
that the materials were piled up into a kind of bank or ridge, and 
that it was the greater part of this ridge which was subsequently 
destroyed by current action. 
Crossing the mouth of the Branscombe valley, the Cenomanian 
beds are found again at the top of Branscombe cliff, coming in 
where this reaches a height of 300 feet. For a little distance, how¬ 
ever, they are not easily accessible. 
In a bluff east of the rock called the Duck and Button there is a 
section which can be reached by climbing, and in which there seem 
to be three distinct beds, no doubt corresponding with Mr. Meyer’s 
10, 11, 12. The succession here is as follows : — 
ft. in. 
T . (Rough nodular chalk, about - - - -60 
luroman.J rocky chalk, with grains of quartz and 
l glauconite, base clearly defined - - - - 1 0 
B. Grey gritty limestone, with a layer of green- 
coated nodules at top - - - - - 010 
A. 2 . Hard shelly and sandy limestone - - -20 
1 . Bough fossiliferous grit, base not seen at this 
exposure, but thickness more than - -40 
Selbornian.—Massive calcareous sandstone, about - 10 0 
Ceno¬ 
manian. 
From this place the fossiliferous grit, Al, is seen to thin out rapidly 
in both directions, letting the next bed, A2, come down on to the 
upper Greensand. Probably there has been some erosion of the 
latter, and Al occupies the hollow so made, but the irregularities 
of the cliff and the growth of grass and bushes make it difficult to 
be sure of this. This Al is clearly the equivalent of the lower part 
of the Bed A at Beer Head and Hooken, and as A2 contains Pecten 
asper, I regard it as the upper part of that bed, B being here very 
thin, and C is not represented. 
This reading is confirmed by another exposure further west, in a 
bluff near the top of the cliff, more than half a mile west of the 
Coastguard Station and above the low-water inlet called the Cove. 
The arrangement of the beds in this bluff is shown in Fig. 34, which 
is taken from a rough sketch made on the spot. 
ft. in. 
Turonian.—Bough whitish chalk, with yellowish nodular 
lumps and yellowish gritty limestone at base - 
Zone 
of Am. 
Mantelli 
B. Bough gritty limestone, loose and weathered 
A2. Hard rough shelly limestone - 
Al. Hard rough calcareous grit, with large r.uartz 
grains and a few fossils, deepens from 6 inches to 
Selbornian. — Massive calcareqqs sandstone - 
8 
0 
1 
3 
16 
0 
9 
4 
0 
0 
